Opened my trunk to check the differential reinforcment welds and found out that the left side of the trunk is full with water! All that side hole is full and also the side mat and the folding mat. Tried to check for leakege from the antena, feels dry.
Tried also to check the rear side of the roof, feels dry.
Any ideas?
Maby there is any kind of blocked rail that leads water to the trunk?
Thanks.
A picture of the water:

The favourite culprit is the 3rd brake light. The seals are pretty old by now, so could need replacing. If you do replace it, bear in mind that it's very difficult to push the light hard enough to clip properly into place with a new seal (but it can give the impression of being properly seated even when it isn't)

A quick test would be to liberally spread talcum powder around inside the boot, then go to work with the hose - the talc will clearly show where water is running, and will help you confirm the source of the leak.

As BladeRuner919 said, the third brake light may well be the culprit. I never had much water in the boot but the bulbs and their holders were rusty, however the aerial base and third brake light seals are old and also looked perished so I replaced them. A new third brake light seal is round or oval in section so pushing it back into position in the boot lid is a bitch to say the least, otherwise as it's been said, the whole lot just pops out again! RockyDave and I (use two of you) found a smear of silicone grease just helped locate the clips. Interestingly the old seal that came out was more flatter, but I assume that was down to nearly 20 years of high compression. I know some have been tempted to use a silicone sealant and mask the problem, but I'd rather have it as it was when new, but be prepared for some 'F'ing and blinding!

Update:
Yesterday i reseal the third brake light and closed the aerial hole with some seal tape and cleaned the trunk.
Woke up this morning and found out that it is full of water again!
It seems that the water is coming from the back of the trunk...
Barry... can u explain a bit more? What is the gutter rail? And what did u do to avoid the leak? Thanks.

had water in mine when i first had the car.. replaced the antenna grommet, but ever since my car has been garaged so dont really know if i have cured the problem.. time will tell when i get out in the car this year in the rain....ihad to syringe the water out there was loads in there... it felt quite oily too the water...the rear 3rd light cover was loose on my car when i had it so suspect someone may have attepmted a repair...

Ok people!
I got the problem!
Stripped the trunk from everything, then puor water all over, then i notice that the rear window is leaking into the car, then into the wiring harness, then the wires took the water into the trunk
Now im going to fix that roof